It's October, hunting season in the Green Mountains, and the Vermont wilderness has never been more beautiful - or more dangerous. Especially for nine-year-old Henry, who's lost in the woods. Again. Only this time, Henry sees something terrible. When a young woman is found shot through the heart with a fatal arrow, former Army MP Mercy Carr thinks that something is murder. But Henry, a math genius whose autism often silences him when he should speak up most, is not talking.

Now there's a murderer hiding among the hunters in the forest and Mercy, along with her retired bomb-sniffing dog Elvis, must team up with their crime-solving friends, game warden Troy Warner and search-and-rescue dog Susie Bear to find the killer... before the killer finds Henry. And with an early-season blizzard fast approaching, time is running out.